The present invention relates to an ultraviolet/infrared absorbent glass having a bronze or gray color shade.
Recently, a variety of glasses with ultraviolet/infrared absorptivity to be used as a vehicle window glass including a windshield have been proposed with a view of preventing degradation of luxurious interior materials and reducing cooling load of the vehicle.
For example, glasses having a green color shade and being improved in the infrared absorptivity and the ultraviolet absorptivity due to including a relatively large amount of Fe2O3 have been developed as a window glass of a vehicle.
A glass having a bronze, brown or gray color shade includes a smaller amount of Fe2O3 than that of the glass having a green color shade and employs ultraviolet absorbing agents including CeO2, TiO2 and V2O5 so as to be provided with the ultraviolet absorptivity. For example, a heat rays absorbent glass having a bronze color shade disclosed in Japanese Patent Publication H6-40741A consists of a base glass including 68 to 74 wt. % SiO2, 0.1 to 3.0 wt. % Al2O3, 2 to 4.5 wt. % MgO, 8 to 11 wt. % CaO, 11.5 to 16 wt. % Na2O, 0.5 to 3.0 wt. % K2O, 0.1 to 0.4 wt. % SO3, 68 to 74 wt. % total amount of SiO2 and Al2O3, 11 to 15 wt. % total amount of CaO and MgO and 12 to 17 wt. % total amount of Na2O and K2O, and colorants including 0.13 to 0.55 wt. % total iron oxide (Txe2x80x94Fe2O3) expressed as Fe2O3, 0.2 to 0.6 wt. % CeO2, 0.15 to 0.45 wt. % TiO2, 0.3 to 14 ppm CoO and 5 to 20 ppm Se, in which the reduction rate of the glass (Fe2+/Fe3+) is between 17% and 55%.
A colored ultraviolet absorbent glass disclosed in Japanese Patent Publication H6-345482A is a glass having a brown color shade consisting of 65 to 75 wt. % SiO2, 0.1 to 5 wt. % Al2O3, 1 to 6 wt. % MgO, 5 to 15 wt. % CaO, 10 to 18 wt. % Na2O, 0 to 5 wt. % K2O, 0.05 to 1.0 wt. % SO3, 0.2 to 1.5 wt. % CeO2, 0 to 1.0 wt. % TiO2, 0 to 0.0015 wt. % CoO, 0.0002 to 0.0012 wt. % Se and 0.2 to 0.4 wt. % Fe2O3, in which Fe2+is in a range of 3 to 15 wt. % among the total amount of Fe.
A colored ultraviolet absorbent glass disclosed in Japanese Patent Publication H6-345483A consists of 65 to 75 wt. % SiO2, 0.1 to 5 wt. % Al2O3, 1 to 6 wt. % MgO, 5 to 15 wt. % CaO, 10 to 18 wt. % Na2O, 0 to 5 wt. % K2O, 0.05 to 1.0 wt. % SO3, 0.4 to 1.0 wt. % CeO2, 0 to 1.0 wt. % TiO2, 0.0018 to 0.0030 wt. % CoO, 0.0001 to 0.0010 wt. % Se and 0.1 to 0.3 wt. % Fe2O3, in which Fe2+is in a range of 3 to 20 wt. % among the total amount of Fe.
A gray glass composition disclosed in Japanese Patent Publication H8-48540A consists of 66 to 75 wt. % SiO2, 0 to 5 wt. % Al2O3, 0 to 5 wt. % MgO, 5 to 15 wt. % CaO, 10 to 20 wt. % Na2O, 0 to 5 wt. % K2O, 0.0003 to 0.0050 wt. % CoO, 0.0001 to 0.0015 wt. % Se, 0.30 to 0.70 wt. % Fe2O3 (total iron), not more than 0.21 wt. % FeO and less than 2.0 wt. % of CeO2, V2O5, TiO2 and MoO3 to be provided with a dull gray color shade.
An ultraviolet/infrared absorbent glass disclosed in Japanese Patent Publication H6-92678A consists of 65 to 80 wt. % SiO2, 0 to 5 wt. % Al2O3, 0 to 5 wt. % B2O3, 0 to 10 wt. % MgO, 5 to 15 wt. % CaO, 10 to 18 wt. % Na2O, 0 to 5 wt. % K2O, 5 to 15 wt. % total amount of MgO and CaO, 10 to 20 wt. % total amount of Na2O and K2O, 0.3 to 2 wt. % cerium oxide expressed as CeO2, 0 to 1 wt. % TiO2, 0.1 to 0.8 wt. % Txe2x80x94Fe2O3, 0 to 0.006 wt. % CoO, 0 to 0.01 wt. % NiO and 0 to 0.0015 wt. % Se.
The conventional ultraviolet/infrared absorbent glasses as referred above are provided with the ultraviolet absorptivity due to a sole action and/or an interaction of one or more than two from among Fe2O3, CeO2, TiO2 and the like, and with the heat rays absorptivity due to FeO added in the form of Fe2O3 and reduced therefrom. However, it is difficult to provide a bronze or gray color shade developed due to Se and a high ultraviolet and infrared absorptivity for the same glass simultaneously.
For example, the glass having a bronze color shade disclosed in Japanese Patent Publication H6-40741A requires relatively large contents of Fe2O3 and TiO2 in order to provide the ultraviolet absorptivity because of its relatively small content of CeO2. In this case, the glass is reduced in the visible light transmittance and the shade is tinged with yellow to become tar tint. It is also difficult to maintain the pink color developed by Se and to provide the bronze or gray color shade in the sight of the present invention for the glass because Se is easy to develop dark brown when the glass includes a large amount of Txe2x80x94Fe2O3.
Each of the glasses having a bronze or gray color shade disclosed in Japanese Patent Publications H6-345482A, H6-345483A and H8-48540A has a disadvantage that indeed the glass has the ultraviolet absorptivity, but is reduced in the infrared absorptivity because the glasses include a small content of FeO in contrast with its large content of Txe2x80x94Fe2O3.
Examples 1 through 18 of the ultraviolet/infrared glass disclosed in Japanese Patent Publication H6-92678 include a small content of Txe2x80x94Fe2O3. These examples except for the example 13 are disadvantageously reduced in the infrared absorptivity and increased in the solar energy transmittance (TG). The example 13 is provided with TG of equal to or less than 65%, while the glass includes 1.46 wt. % CeO2 in order to be balanced against the visible light transmittance and the ultraviolet transmittance thereof. CeO2, is not preferable to be used in large amounts because of its expensive cost.
It is an object of the present invention to solve conventional problems described above and provide an ultraviolet/infrared absorbent glass having a bronze or gray color shade which is provided with a high ultraviolet and infrared absorptivity.
The ultraviolet/infrared absorbent glass of the present invention consists of a base glass comprising:
65 to 80 wt. % SiO2;
0 to 5 wt. % B2O3;
0 to 5 wt. % Al2O3;
0 to 10 wt. % MgO;
5 to 15 wt. % CaO;
10 to 18 wt. % Na2O;
0 to 5 wt. % K2O;
5 to 15 wt. % total amount of MgO and CaO; and
10 to 20 wt. % total amount of Na2O and K2O, colorants including:
equal to or more than 0.05 wt. % and less than 0.2 wt. % total iron oxide (Txe2x80x94Fe2O3) expressed as Fe2O3;
0.63 to 1.4 wt. % CeO2;
0.02 to 1.5 wt. % TiO2;
0.0005 to 0.005 wt. % CoO; and
0.0003 to 0.002 wt. % Se.
In the glass of the present invention FeO expressed as Fe2O3 is between 30 wt. % and 60 wt. % of Txe2x80x94Fe2O3.
The ultraviolet/infrared absorbent glass may further comprise 0.001 to 0.01 wt. % NiO so as to adjust its color of the shade.
The ultraviolet/infrared absorbent glass is preferable to include 0.01 to 1 wt. % La2O3.
The ultraviolet/infrared absorbent glass at any thickness between 2.6 mm and 6.3 mm is preferable to be provided with the visible light transmittance of equal to or more than 65% when measured by using the CIE illuminant A, the solar energy transmittance of equal to or less than 65% when measured over a wavelength between 300 nm and 2100 nm and the ultraviolet transmittance specified by ISO of equal to or less than 20%.
The ultraviolet/infrared absorbent glass at any thickness between 2.6 mm and 6.3 mm is preferable to be provided with the excitation purity of equal to or less than 10% when measured by using the CIE illuminant C and a bronze color shade having the chromaticity expressed as a* and b* defined by the L*a*b* coordinates in ranges of xe2x88x922xe2x89xa6a*xe2x89xa61 and 4xe2x89xa6b*xe2x89xa610.
The ultraviolet/infrared absorbent glass at any thickness between 2.6 mm and 6.3 mm is preferable to be provided with the excitation purity of equal to or less than 5% when measured by using the CIE illuminant C and a gray color shade having the chromaticity expressed as a* and b* defined by the L*a*b* coordinates in ranges of xe2x88x922xe2x89xa6a*xe2x89xa61 and xe2x88x921xe2x89xa6b*xe2x89xa64.